Rob van Hest Capture-recapture Methods in Surveillance - RePub ...

Chapter 11
of the proportion of false-positive records through complex mathematical procedures for
infectious disease capture-recapture analysis has been described previously. 22 The
estimated proportions of false-positive records in the hospital register or among unlinked
hospitalised cases were similar to those found in a previous local capture-recapture study
in England8 and in the studies in the Netherlands and the Piedmont region of Italy. The
cross-validation of non-culture-confirmed cases also limited violation of the perfect
positive predictive value assumption but it cannot be excluded. The log-linear capturerecapture
model with the best goodness-of-fit was the saturated model. As discussed in
the answer to research question 1, violation of the absent (positive) three-way interaction
assumption is unlikely to explain the implausible high estimate. 22 According to Hook and
Regal, if the saturated model is selected by any criterion the investigator should be
particularly cautious about using the associated outcome. 11 In the Netherlands the initial
saturated capture-recapture model also gave unexpected and implausible high estimates of
the number of unobserved tuberculosis patients. All three-source log-linear capturerecapture
studies on tuberculosis and other infectious diseases incidence presented in
Table 1.1 and 3.1 used independent or parsimonious log-linear models, apart from the
capture-recapture study on meningitis incidence in the Netherlands by De Greeff et al.
The only other published capture-recapture study using a saturated model was Chao’s
study on hepatitis A in Taiwan, discussed in chapter 10. Perhaps the validity of capturerecapture
results reflects publication bias in favour of successful capture-recapture studies
rather than the inherent strength of the methodology. 23 Stratification by relevant
covariates associated with the probability of capture, to identify possible violation of the
homogeneous population assumption, was not feasible. A truncated Poisson mixture
model, arguably more robust in the presence of heterogeneity, estimated a considerably
lower annual and total number of tuberculosis patients, with a smaller confidence interval.
We can neither prove nor exclude that the estimates of the alternative truncated model
portray a more accurate estimate of the true number of tuberculosis patients in England.
Comparison of the results of the three tuberculosis capture-recapture studies
Table 11.1 shows the completeness of three tuberculosis registers in the Netherlands, the
Piedmont region in Italy and England, ascertained after record-linkage and estimated after
capture-recapture analysis. To calculate the capture-recapture estimates in the
Netherlands SPSS statistical software was used, in Italy S-PLUS software with the CARE
library24 and in England Stata software, but these different tools should produce similar
results.
Notification:
After record-linkage initially the ascertained completeness of the notification registers is
similar it but becomes higher in the Netherlands after the correction for possibly
imperfect record-linkage and possibly imperfect positive predictive value of the hospital
register, probably reflecting the good organisation of tuberculosis surveillance.
After capture-recapture analysis, the estimated completeness of the notification
register is highest in the Netherlands and slightly lower in Italy. The estimated
completeness of the notification register in England is highly inconsistent with the two
other estimates.
166